The Role of Dietary Cholesterol in Lipoprotein Metabolism and Related Metabolic Abnormalities: A Mini-review

High Density Lipoprotein from Egg Yolk (EYHDL) Improves Dyslipidemia by Mediating Fatty Acids Metabolism in High Fat Diet-induced Obese Mice

We investigated the effect of high density lipoprotein from egg yolk (EYHDL) on serum, hepatic and fecal lipid and fatty acids (FAs) levels and on gene expression involved in FAs metabolism. Male KM mice were fed either normal diet (ND; n=20), high fat diet (HFD; n=20), or high fat diet containing EYHDL (EYHDL; 0.6 mg/g, every day by oral gavage, n=20) for 100 days. At the end of the experiment, the effects of treatments on biochemical parameters, FAs profiles and involved gene expression were analyzed. Our results revealed that EYHDL markedly suppressed the body weight gain, accumulation of abdominal fat tissues, serum concentrations of LDL-cholesterol (LDL-C) and triglycerides, hepatic triglycerides and cholesterol accumulation, while increased serum concentration of HDL-cholesterol (HDL-C). EYHDL intake also increased total cholesterol (TC) excretions compared with HFD group. Moreover, it alleviated the severity of fatty liver and improved glucose and insulin tolerance compared with HFD. More importantly, EYHDL partially normalized FAs profiles in serum, liver and fecaces and neutralized the HFD-induced upregulation of SREBP-1c, Acaca, Fasn, GPAT and Scd1. In conclusion, our findings indicate that EYHDL may have the potential to improve metabolic disturbances that occur in HFD mice and can be considered as an appropriate dietary recommendation for the treatment of metabolic syndrome (MetS).

Cynanchum wilfordii Etanolic Extract Controls Blood Cholesterol: A Double-blind, Randomized, Placebo-Controlled, Parallel Trial

We evaluated the effects of Cynanchum wilfordii (CW) ethanolic extract on blood cholesterol levels in adults with high low-density lipoprotein cholesterol (LDL-C) levels. In a double-blind, randomized, placebo-controlled, parallel trial, 84 subjects were recruited. Participants were randomly divided into two groups with a low-dose (300 mg/d) or high-dose (600 mg/d) of CW. Levels of very low-density lipoprotein (p = 0.022) and triglycerides (p = 0.022) were significantly lower in the low-dose CW group than in the placebo group after 8 weeks. In a subgroup of participants with LDL-C≥ 150 mg/dL (n = 33), there was a significant decrease in total cholesterol (low-dose, p = 0.012; high-dose, p = 0.021), apolipoprotein B (low-dose, p = 0.022; high-dose, p = 0.016), and cholesteryl ester transfer protein (low-dose, p = 0.037; high-dose, p = 0.016) after 8 weeks of CW. The correlation between changes in total cholesterol and baseline LDL-C levels was significant in the groups that received both doses of CW (low-dose, p = 0.010; high-dose, p = 0.015). These results show that the CW ethanolic extract can regulate blood cholesterol in subjects with LDL-C≥ 150 mg/dL.

Metabolic syndrome and associated factors in Iranian children and adolescents: the CASPIAN-V study

Introduction:Metabolic syndrome (MetS) is one of the common metabolic disorders seen in children and adolescents. This study aims to assess the rate of the MetS and its associated factors in a nationally-representative sample of Iranian pediatric age groups.

Methods: This nationwide cross- sectional study was designed in 2015 in 30 provinces of Iran. Participants consisted of 4,200 school students, aged 7-18 years, studied in a national school-based surveillance program (CASPIAN-V). Physical examination and laboratory tests were performed using standard protocols. Blood samples were drawn from 3834 students for biochemical tests.

Results: The participation rate for blood sampling was 91.5%. MetS was significantly more prevalent among students in urban than in rural areas (5.7% vs. 4.8%, P value < 0.01). MetS was more prevalent in students with obese parents than in those with non-obese parents (6.4% vs. 4.5%, P value < 0.05). Significant association existed between moderate level of healthy nutritional behaviors and MetS after controlling for potential confounders (odds ratio [OR]: 0.62, 95% CI: 0.40-0.98). Students with high unhealthy nutritional behaviors showed an increased risk of MetS in crude (OR: 1.6, 95% CI: 1.05-2.44) and adjusted model (OR: 1.65, 95% CI: 1.05-2.63).

Conclusion: High rate of MetS and associated risk factors was observed in Iranian pediatric age groups, with higher rates among boys. These findings provide useful information for effective preventive strategies based on diet, exercise, and lifestyle modification rather than therapeutic modalities.

Biomarker of food intake for assessing the consumption of dairy and egg products

Dairy and egg products constitute an important part of Western diets as they represent an excellent source of high-quality proteins, vitamins, minerals and fats. Dairy and egg products are highly diverse and their associations with a range of nutritional and health outcomes are therefore heterogeneous. Such associations are also often weak or debated due to the difficulty in establishing correct assessments of dietary intake. Therefore, in order to better characterize associations between the consumption of these foods and health outcomes, it is important to identify reliable biomarkers of their intake. Biomarkers of food intake (BFIs) provide an accurate measure of intake, which is independent of the memory and sincerity of the subjects as well as of their knowledge about the consumed foods. We have, therefore, conducted a systematic search of the scientific literature to evaluate the current status of potential BFIs for dairy products and BFIs for egg products commonly consumed in Europe. Strikingly, only a limited number of compounds have been reported as markers for the intake of these products and none of them have been sufficiently validated. A series of challenges hinders the identification and validation of BFI for dairy and egg products, in particular, the heterogeneous composition of these foods and the lack of specificity of the markers identified so far. Further studies are, therefore, necessary to validate these compounds and to discover new candidate BFIs. Untargeted metabolomic strategies may allow the identification of novel biomarkers, which, when taken separately or in combination, could be used to assess the intake of dairy and egg products.

The Association of Dietary Cholesterol and Fatty Acids with Dyslipidemia in Chinese Metropolitan Men and Women

BACKGROUND

The associations between dietary cholesterol and fatty acids and serum lipids are controversial. This study is to examine the association of dietary cholesterol and fatty acids with serum lipids and dyslipidemia in Chinese metropolitan male and female adults.

METHODS

3850 participants in the Shanghai Diet and Health Survey were investigated during the period 2012⁻2013. Information was obtained on dietary intake, anthropometric and blood laboratory measurements. Dyslipidemia was determined by US National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III).

RESULTS

Dietary cholesterol was in line with serum TC, LDL-C and the LDL-C to HDL-C ratio in general and the partial correlation coefficients were 0.64 (95% CI: 0.13⁻1.15, p = 0.015), 0.73 (95% CI: 0.21⁻1.24, p = 0.006) and 0.01 (95% CI: 0.00⁻0.02, p = 0.018), respectively. The partial correlation coefficients were greater in women. Dietary fatty acids were not associated with serum lipids. The highest quintile of dietary cholesterol intake (≥538.0 mg/day) was associated with an approximate 1.6-fold risk for high TC and high HDL-C compared with the lowest quintile (<193.1 mg/day) generally.

CONCLUSIONS

Dietary cholesterol was associated with serum cholesterol in Chinese metropolitan adults and a higher risk of dyslipidemia was observed at a high level of dietary cholesterol intake. Whether there should be an upper limit on dietary cholesterol in the Chinese population warrants further study.

Genomic profiling of bovine corpus luteum maturation

To unveil novel global changes associated with corpus luteum (CL) maturation, we analyzed transcriptome data for the bovine CL on days 4 and 11, representing the developing vs. mature gland. Our analyses revealed 681 differentially expressed genes (363 and 318 on day 4 and 11, respectively), with ≥2 fold change and FDR of <5%. Different gene ontology (GO) categories were represented prominently in transcriptome data at these stages (e.g. days 4: cell cycle, chromosome, DNA metabolic process and replication and on day 11: immune response; lipid metabolic process and complement activation). Based on bioinformatic analyses, select genes expression in day 4 and 11 CL was validated with quantitative real-time PCR. Cell specific expression was also determined in enriched luteal endothelial and steroidogenic cells. Genes related to the angiogenic process such as NOS3, which maintains dilated vessels and MMP9, matrix degrading enzyme, were higher on day 4. Importantly, our data suggests day 11 CL acquire mechanisms to prevent blood vessel sprouting and promote their maturation by expressing NOTCH4 and JAG1, greatly enriched in luteal endothelial cells. Another endothelial specific gene, CD300LG, was identified here in the CL for the first time. CD300LG is an adhesion molecule enabling lymphocyte migration, its higher levels at mid cycle are expected to support the transmigration of immune cells into the CL at this stage. Together with steroidogenic genes, most of the genes regulating de-novo cholesterol biosynthetic pathway (e.g HMGCS, HMGCR) and cholesterol uptake from plasma (LDLR, APOD and APOE) were upregulated in the mature CL. These findings provide new insight of the processes involved in CL maturation including blood vessel growth and stabilization, leucocyte transmigration as well as progesterone synthesis as the CL matures.

Blackcurrant anthocyanins stimulated cholesterol transport via post-transcriptional induction of LDL receptor in Caco-2 cells

PURPOSES

We previously showed that polyphenol-rich blackcurrant extract (BCE) showed a hypocholesterolemic effect in mice fed a high fat diet. As direct cholesterol removal from the body via the intestine has been recently appreciated, we investigated the effect of BCE on the modulation of genes involved in intestinal cholesterol transport using Caco-2 cells as an in vitro model.

METHODS

Caco-2 cells were treated with BCE to determine its effects on mRNA and protein expression of genes important for intestinal cholesterol transport, low-density lipoprotein (LDL) uptake, cellular cholesterol content, and cholesterol transport from basolateral to apical membrane of Caco-2 cell monolayers. Cells were also treated with anthocyanin-rich or -poor fraction of BCE to determine the role of anthocyanin on BCE effects.

RESULTS

BCE significantly increased protein levels of LDL receptor (LDLR) without altering its mRNA, which consequently increased LDL uptake into Caco-2 cells. This post-transcriptional induction of LDLR by BCE was markedly attenuated in the presence of rapamycin, an inhibitor of mechanistic target of rapamycin complex 1 (mTORC1). In addition, BCE altered genes involved in cholesterol transport in the enterocytes, including apical and basolateral cholesterol transporters, in such a way that could enhance cholesterol flux from the basolateral to apical side of the enterocytes. Indeed, BCE significantly increased the flux of LDL-derived cholesterol from the basolateral to the apical chamber of Caco-2 monolayer. LDLR protein levels were markedly increased by anthocyanin-rich fraction, but not by anthocyanin-free fraction.

CONCLUSION

mTORC1-dependent post-transcriptional induction of LDLR by BCE anthocyanins drove the transport of LDL-derived cholesterol to the apical side of the enterocytes. This may represent a potential mechanism for the hypocholesterolemic effect of BCE.

Relationship between dietary factors and the number of altered metabolic syndrome components in Chinese adults: a cross-sectional study using data from the China Health and Nutrition Survey

OBJECTIVES

To study the correlation between dietary factors and the number of altered metabolic syndrome components (MetS) in Chinese adults systematically.

SETTING

A cross-sectional study using demographic and dietary data of adults aged 18-75 years from the China Health and Nutrition Survey (2009) was conducted in nine provinces in China.

PARTICIPANTS

There were 6034 eligible subjects (2800 men and 3234 women) in this study.

OUTCOMES

The primary outcome of this study were diet assessments and the number of altered MetS components. Dietary intake was measured using a combination of a 3-day period with 24-hour and household food inventory; average daily intakes of nutrients were estimated according to the Chinese Food Composition Table. Blood samples were analysed in a national central laboratory and the number of clustering MetS components was calculated by adding the presence of each MetS component.

RESULTS

After adjusting for covariates, and taking zero MetS as comparison, the high risk factors correlating with increased numbers of altered MetS components in men were higher intake of protein (70.4-73.4 g; Ptrend=0.0004), cholesterol (238.7-266.6 mg; Ptrend=0.004), meat (90.6-105.7 g; Ptrend=0.016), fish/seafood (30.4-42.3 g; Ptrend=0.001), and lower intake of coarse cereals (16.5-12.7 g; Ptrend=0.051), tubers (37.3-32.7 g; Ptrend=0.030), and dietary fibre (11.7-11.5 g; ANCOVA p=0.058). Meanwhile, the high risk factors correlating with the increased number of altered MetS components in women were higher intake of wheat (101.9-112.6 g; Ptrend=0.066) and sodium (3862.3-4005.7 mg, Ptrend=0.032), and lower intake of β-carotene (1578.6-1382.7 µg; Ptrend=0.007), milk, and dairy products (17.8-11.5 g; Ptrend=0.002).

CONCLUSIONS

Some foods and nutritional factors correlate with an increased number of altered MetS components in Chinese adults. More prospective, multicentre and clinical research work to further examine these associations is underway.

A Cross-Sectional Study of the Prevalence of Metabolic Syndrome and Associated Factors in Colombian Collegiate Students: The FUPRECOL-Adults Study

Metabolic syndrome (MetS) is one of the major public health problems worldwide. The objective of the present study is to investigate the prevalence and the associated variables of MetS in Colombian collegiate students. This cross-sectional study included a total of 890 (52% women) healthy collegiate students (21.3 ± 3.2 years old). The prevalence of MetS was determined by the definition provided by the International Diabetes Federation (IDF). We further examined associations between the prevalence of MetS and related factors, such as age, gender, anthropometric and body composition, weight status, and nutrition profile. The overall prevalence of MetS was 6.0% (95% CI = 4.5% to 7.6%), and it was higher in men than women. The most prevalent components were low high-density lipoprotein cholesterol, high triglyceride levels, waist circumference, and blood pressure levels. The predisposing factors for having a MetS included: being male, over 23 years old, overweight or obese, and having an unhealthy waist-to-height ratio. In conclusion, the occurrence of MetS in young adults is substantial. These findings may be relevant to health promotion efforts for collegiate students in order to develop prospective studies and screening for young adults, which will aid in targeted intervention development to decrease cardiometabolic risk factors.

The association between dietary cholesterol intake and subclinical atherosclerosis in Korean adults: The Kangbuk Samsung Health Study

BACKGROUND

The Scientific Report of the Dietary Guidelines Advisory Committee (2015) concluded that restriction of dietary cholesterol is unnecessary in most adults for the prevention of cardiovascular disease.

OBJECTIVE

We aimed to assess the risk for subclinical atherosclerosis according to coronary artery calcium score (CACS), based on dietary cholesterol intake in apparently healthy Korean adults.

METHODS

This was a cross-sectional study performed in 30,068 participants (mean age 40.8 years; 84.5% men) in a health screening program in Korea. The data were collected from 2001 to 2013 and analyzed in 2015. Total energy intake and dietary cholesterol intake were assessed with a food frequency questionnaire. The participants were stratified according to quartile of dietary cholesterol intake. CACS was measured by multi-detector computed tomography. Lipid profiles were measured, and the participants were divided into 6 groups according to low-density lipoprotein cholesterol (LDL-C) level: <70, 70 to 99, 100 to 129, 130 to 159, 160 to 189, and ≥190 mg/dL.

RESULTS

The presence of coronary artery calcification was defined as CACS>0. Dietary cholesterol intake did not correlate with mean value of serum LDL-C level. For both genders, the odds ratio for coronary artery calcification was not significantly greater with greater amounts of dietary cholesterol (as assessed by quartile). The risk for coronary artery calcification was not higher in subjects with LDL-C 70-129 mg/dL compared with those with LDL-C < 70 mg/dL; however, the risk was significantly greater in subjects with LDL-C ≥ 130 mg/dL compared with those with LDL-C < 70 mg/dL.

CONCLUSIONS

Dietary cholesterol intake did not have an association with LDL-C level or with risk for coronary artery calcification in apparently healthy Korean adults. The results have to be translated with consideration of limitation of population-based studies.